1. Field of the Invention
This invention pertains to high density mobile storage, and more particularly to apparatus that controls the movement of mobile carriages.
2. Description of the Prior Art
Electrically powered mobile carriages for high density mobile storage are well developed. The mobile carriages are operated by a control system to move individually or as a group, depending on the location of a carriage and the particular aisle access required by the operator.
The control system typically includes a small operator housing containing manual switches and buttons. The operator housing is normally on an end panel of the carriage, where it is easily accessible to the operator. Typical control systems are generally shown in U.S. Pat. Nos. 4,119,376, 4,733,923, 4,743,078, 5,160,190, and 5,569,910. U.S. Pat. No. 5,050,941 and U.S. Pat. No. Des. 331,388 show a mobile carriage switch assembly and control panel in some detail.
Prior mobile carriage control systems also included a module of electronic components on each carriage. The control modules were connected by electrical cables to the operator housings. The control modules typically receive line power and convert it to power suitable for driving the carriage motors. The modules also pass the line power to adjacent carriages.
The manual buttons and switches of prior mobile carriage control systems were strictly utilitarian. That is, the various switches and buttons performed their respective functions adequately but without regard for aesthetic considerations. Moreover, the prior buttons and switches gave minimal attention to any intuitive considerations of an operator as he made his decisions when operating the mobile carriages. In addition, the prior design of separate operator housings and electronic modules connected by a cable was undesirably expensive.
To enhance the appearance and ergonomics of high density mobile storage, a new interface between the mobile carriages and the operators was proposed. The new interface was to include a cluster of operating buttons incorporated into the interior of a frame. In keeping with the purpose of the buttons, they were to be made relatively long compared with their width, and they were to be shaped and located to conform to the intuition of an operator. Further, acrylonitrile butadiene styrene (ABS) copolymer plastic was the preferred material, because very attractive parts could be made from that material.
However, two problems arose in trying to design the combined button-frame interface. The first problem was that a relatively long and narrow button requires some kind of a leveling mechanism so that it does not cock and bind in the frame when the button is depressed. One solution was to use thin wires retained in the frame and in the undersides of the buttons. However, the molds required for the proposed new mobile carriage interface with leveling wires between the frame and the buttons were prohibitively expensive for the relatively small volume of parts used with high density mobile storage. It was therefore necessary to find a way to self-level the buttons through a direct connection between the buttons and the frame. That necessity dictated that hinged connections be used between the buttons and the frame.
A hinged design raised the second problem, which is that ABS plastic material is generally unsuitable for parts that must flex during operation. If the hinge connection is relatively long and straight, ABS can work. For example, U.S. Pat. Nos. 4,375,585, 4,703,160, 4,786,892, 5,184,283; and 5,828,364 show various devices in which straight living hinges of ABS material extend for the full length of the parts hinged together. In the proposed mobile carriage interface, however, aesthetic considerations dictate that only curved sides be used on all the buttons.
Thus, a number of problems required solution to achieve a successful mobile carriage interface design.